Chiral distortion of confined ice oligomers (N = 5,6).

Ice nuclei have been studied on the hexagonal boron nitride nanomesh (h-BN/Rh(111)), a template with 2 nm wide molecule traps. Scanning tunneling microscopy shows confined clusters, where oligomers with three protrusions are particularly abundant. Together with local barrier height dI/dz maps, it is found that the dipoles of the water molecules arrange in a homodrome, which is consistent with density functional theory calculations. Hydrogen bonds toward the substrate identify h-BN/Rh(111) to be hydrophilic. The substrate distorts the hexamers (n = 6) and possibly pentamers (n = 5), where the experimentally observed footprints of the three protrusions appear more chiral than expected.